The neural substrates of the warning effect: A functional magnetic resonance imaging study

To test the hypothesis the warning effect is mediated by the top-down attentional modulation of the motor system, we conducted functional MRI using a Go/No-Go task with visual and auditory warning stimuli. For aurally-warned, visually-prompted trials, the auditory warning stimulus was presented for 1500 ms, during which visual cues were presented that prompted either Go or No-Go responses. The same format was used for visually-warned, aurally-prompted trials. Both auditory and visual warning cues shortened the reaction time for the Go trials. The warning cues activated the right-lateralized parieto-frontal top-down attentional network, and motor cortical areas including the pre-supplementary motor area (pre-SMA), the bilateral dorsal premotor cortex, and the left primary motor cortex (M1). The warning-related activation of the pre-SMA matched the difference between its activation by Go-with-warning and by Go-without-warning. Thus, the pre-SMA was primed by the warning cue. The same pre-SMA priming effect was observed for the No-Go cue-related activation, consistent with its role in movement preparation and selection. Similar but less prominent Go cue-related priming was observed in the M1. Thus, the warning effect represents the pre-potentiation of the motor control pathway by the top-down attentional system, from the selection and preparation of the movement to its execution. (C) 2013 The Authors. Published by Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.